Various techniques for routing packets through communication networks are known in the art. Some known techniques select routing paths for packets based on the network state, e.g., traffic load or congestion. Such techniques are sometimes referred to as Adaptive Routing. AR techniques are described, for example, by Kim et al., in “Adaptive Routing in High-Radix Clos Network,” Proceedings of the 2006 ACM/IEEE Conference on Supercomputing (SC2006), Tampa, Fla., November 2006, which is incorporated herein by reference.